Field of the Invention
The present invention relates to articulated loading arms for transferring fluid such as gasoline or other petroleum products into a transport vessel, such as a tank truck or railway tank car. More particularly, the present invention relates to systems for controlling the movement of fluid loading arms as they are maneuvered into and out of their functional positions.
Articulated loading arms for delivery of gasoline and other fluids into truck and railway tankers usually include a drop pipe at the outer end for insertion into a filler hatch in the top of the tank, the drop pipe then being lowered to a position close to the bottom of the tank. The maneuverability of these arms must be adequate to enable the drop pipe to be positioned precisely over the tank hatch even though the hatch is not in its designated loading location, and also to facilitate lowering the drop pipe into the tank, and lifting it out of tank, along an absolutely vertical path so that no change occurs in the pipe's azimuthal position.
For this purpose, known articulated fluid loading arms comprise an inboard arm section pivotally mounted on a suitable support for movement about horizontal and vertical axes, an outboard arm section pivotally connected to the inboard arm section for movement about another horizontal axis, and a drop pipe pivotally connected to the outer end of the outboard arm section and depending vertically therefrom, the inboard and outboard arm sections and the drop pipe together comprising a fluid-tight conduit. Suitable linkages are employed to facilitate vertical movement of the drop pipe, and counterweights usually are included to balance the entire assembly, which assembly is sometimes mounted on a movable carriage. Due to the importance of raising and lowering the drop pipe in a strictly vertical path regardless of where the tank filler hatch is situated, the assembly generally is complicated and often relatively heavy and cumbersome, and consequently manufacturing costs are unusually high.
There also is known, notably in the field of public works, articulated loading arm equipment wherein the various sections of the arm are pivotable relative to one another by actuating devices, such as hydraulic or pneumatic jacks. However, in these arm assemblies, each actuating device has to be operated separately, so that moving the drop pipe in an absolutely vertical path requires the equipment operator to have perfect coordination and unusually great dexterity.